My engine runs warm when I idle or am in slow moving traffic. But when I am doing over 50mph the engine runs cold (right down to the C). We do oil change every 3,000 miles and now need to replenish 2 quarts every 1500 miles. Any idea what is happening or what we should look into. Would like to make this car last to 250,000 miles. Help!
Oil consumption and overheating are two different things. Your oil consumption is normal for that many miles. Use a good grade of 10W30 high mileage oil.
The symptoms sound like you need to change your thermostat. A T-stat controls the minimum operating temperature of an engine. At 50 your gauge should be in the middle. Put in the correct temp t-stat. DON" T reduce the temperature.
If you have no T-stat the engine will overheat at slow speeds because the coolant flows through the engine too fast, not giving it enough time to cool.
Make sure you have good flow through your radialtor. If you have never changed the coolant the radiator is clogged with mineral deposits. Let me know.